Peat moss-derived biochar for sonocatalytic applications

Peat-moss derived biochar was used as a sonocatalyst for the degradation of rhodamine B (RhB) at different ultrasonic frequencies (40 kHz and 300 kHz). The biochar was prepared by pyrolysis of peat-moss at 300 °C under N₂-saturated conditions. High removal efficiency was achieved when biochar (1000 mg L⁻¹) was used as a sonocatalyst in the 40 kHz system, and high removal could be achieved by pre-adsorption and radical oxidation reactions on the surface of the biochar. This was validated in experiments employing radical scavengers. Sonochemiluminescence images and real images of the systems with no biochar, 100 mg L⁻¹ biochar, and 1000 mg L⁻¹ biochar also supported this observation. On the other hand, the addition of the biochar was less effective than expected for the degradation of RhB at 300 kHz. This was due to low dispersion of the biochar in solution in the high frequency system, where relatively weaker sonophysical effects could be obtained.